/*!
 * CrossSlide jQuery plugin v0.4.1
 *
 * Copyright 2007-2010 by Tobia Conforto <tobia.conforto@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */
/* Changelog:
 *
 * 0.4.1  2010-06-04  Added target option
 * 0.4    2010-05-20  Better error reporting, published on GitHub
 * 0.3.7  2009-05-14  Fixed bug when container div's CSS position is not set
 * 0.3.6  2009-04-16  Added alt option
 * 0.3.5  2009-03-12  Fixed usage of href parameter in 'Ken Burns' mode
 * 0.3.4  2009-03-12  Added shuffle option,
 *                    contrib. by Ralf Santbergen <ralf_santbergen@hotmail.com>
 * 0.3.3  2008-12-14  Added onclick option
 * 0.3.2  2008-11-11  Fixed CSS bugs, contrib. by Erwin Bot <info@ixgcms.nl>
 * 0.3.1  2008-11-11  Better error messages
 * 0.3    2008-10-22  Option to repeat the animation a fixed number of times
 * 0.2    2008-10-15  Linkable images, contrib. by Tim Rainey <tim@zmlabs.com>
 * 0.1.1  2008-09-18  Compatibility with prototype.js
 * 0.1    2008-08-21  Re-released under GPL v2
 * 0.1    2007-08-19  Initial release
 */

jQuery.fn.crossSlide = function (opts, plan) {
  var self = this,
    self_width = this.width(),
    self_height = this.height();

  // generic utilities
  function format(str) {
    for (var i = 1; i < arguments.length; i++)
      str = str.replace(new RegExp('\\{' + (i - 1) + '}', 'g'), arguments[i]);
    return str;
  }

  function abort() {
    arguments[0] = 'CrossSlide: ' + arguments[0];
    throw new Error(format.apply(null, arguments));
  }

  // first preload all the images, while getting their actual width and height
  (function (proceed) {

    var n_loaded = 0;

    function loop(i, img) {
      // this loop is a for (i = 0; i < plan.length; i++)
      // with independent var i, img (for the closures)
      img.onload = function (e) {
        n_loaded++;
        plan[i].width = img.width;
        plan[i].height = img.height;
        if (n_loaded == plan.length)
          proceed();
      }
      img.src = plan[i].src;
      if (i + 1 < plan.length)
        loop(i + 1, new Image());
    }

    loop(0, new Image());

  })(function () { // then proceed

    // utility to parse "from" and "to" parameters
    function parse_position_param(param) {
      var zoom = 1;
      var tokens = param.replace(/^\s*|\s*$/g, '').split(/\s+/);
      if (tokens.length > 3) throw new Error();
      if (tokens[0] == 'center')
        if (tokens.length == 1)
          tokens = ['center', 'center'];
        else if (tokens.length == 2 && tokens[1].match(/^[\d.]+x$/i))
          tokens = ['center', 'center', tokens[1]];
      if (tokens.length == 3)
        zoom = parseFloat(tokens[2].match(/^([\d.]+)x$/i)[1]);
      var pos = tokens[0] + ' ' + tokens[1];
      if (pos == 'left top' || pos == 'top left')
        return { xrel:0, yrel:0, zoom:zoom };
      if (pos == 'left center' || pos == 'center left')
        return { xrel:0, yrel:.5, zoom:zoom };
      if (pos == 'left bottom' || pos == 'bottom left')
        return { xrel:0, yrel:1, zoom:zoom };
      if (pos == 'center top' || pos == 'top center')
        return { xrel:.5, yrel:0, zoom:zoom };
      if (pos == 'center center')
        return { xrel:.5, yrel:.5, zoom:zoom };
      if (pos == 'center bottom' || pos == 'bottom center')
        return { xrel:.5, yrel:1, zoom:zoom };
      if (pos == 'right top' || pos == 'top right')
        return { xrel:1, yrel:0, zoom:zoom };
      if (pos == 'right center' || pos == 'center right')
        return { xrel:1, yrel:.5, zoom:zoom };
      if (pos == 'right bottom' || pos == 'bottom right')
        return { xrel:1, yrel:1, zoom:zoom };
      return {
        xrel:parseInt(tokens[0].match(/^(\d+)%$/)[1]) / 100,
        yrel:parseInt(tokens[1].match(/^(\d+)%$/)[1]) / 100,
        zoom:zoom
      };
    }

    // utility to compute the css for a given phase between p.from and p.to
    // 1: begin fade-in, 2: end fade-in, 3: begin fade-out, 4: end fade-out
    function position_to_css(p, phase) {
      switch (phase) {
        case 1:
          var pos = 0;
          break;
        case 2:
          var pos = fade_ms / (p.time_ms + 2 * fade_ms);
          break;
        case 3:
          var pos = 1 - fade_ms / (p.time_ms + 2 * fade_ms);
          break;
        case 4:
          var pos = 1;
          break;
      }
      return {
        left:Math.round(p.from.left + pos * (p.to.left - p.from.left)),
        top:Math.round(p.from.top + pos * (p.to.top - p.from.top)),
        width:Math.round(p.from.width + pos * (p.to.width - p.from.width)),
        height:Math.round(p.from.height + pos * (p.to.height - p.from.height))
      };
    }

    // check global params
    if (!opts.fade)
      abort('missing fade parameter.');
    if (opts.speed && opts.sleep)
      abort('you cannot set both speed and sleep at the same time.');

    // conversion from sec to ms; from px/sec to px/ms
    var fade_ms = Math.round(opts.fade * 1000);
    if (opts.sleep)
      var sleep = Math.round(opts.sleep * 1000);
    if (opts.speed)
      var speed = opts.speed / 1000,
        fade_px = Math.round(fade_ms * speed);

    // set container css
    self.empty().css({
      overflow:'hidden',
      padding:0
    });
    if (!/^(absolute|relative|fixed)$/.test(self.css('position')))
      self.css({ position:'relative' });
    if (!self.width() || !self.height())
      abort('container element does not have its own width and height');

    // random sorting
    if (opts.shuffle)
      plan.sort(function () {
        return Math.random() - 0.5;
      });

    // prepare each image
    for (var i = 0; i < plan.length; ++i) {

      var p = plan[i];
      if (!p.src)
        abort('missing src parameter in picture {0}.', i + 1);

      if (speed) { // speed/dir mode

        // check parameters and translate speed/dir mode into full mode
        // (from/to/time)
        switch (p.dir) {
          case 'up':
            p.from = { xrel:.5, yrel:0, zoom:1 };
            p.to = { xrel:.5, yrel:1, zoom:1 };
            var slide_px = p.height - self_height - 2 * fade_px;
            break;
          case 'down':
            p.from = { xrel:.5, yrel:1, zoom:1 };
            p.to = { xrel:.5, yrel:0, zoom:1 };
            var slide_px = p.height - self_height - 2 * fade_px;
            break;
          case 'left':
            p.from = { xrel:0, yrel:.5, zoom:1 };
            p.to = { xrel:1, yrel:.5, zoom:1 };
            var slide_px = p.width - self_width - 2 * fade_px;
            break;
          case 'right':
            p.from = { xrel:1, yrel:.5, zoom:1 };
            p.to = { xrel:0, yrel:.5, zoom:1 };
            var slide_px = p.width - self_width - 2 * fade_px;
            break;
          default:
            abort('missing or malformed dir parameter in picture {0}.', i + 1);
        }
        if (slide_px <= 0)
          abort('picture {0} is too small for the desired fade duration.', i + 1);
        p.time_ms = Math.round(slide_px / speed);

      } else if (!sleep) { // full mode

        // check and parse parameters
        if (!p.from || !p.to || !p.time)
          abort('missing either speed/sleep option, or from/to/time params '
            + 'in picture {0}.', i + 1);
        try {
          p.from = parse_position_param(p.from)
        } catch (e) {
          abort('malformed "from" parameter in picture {0}.', i + 1);
        }
        try {
          p.to = parse_position_param(p.to)
        } catch (e) {
          abort('malformed "to" parameter in picture {0}.', i + 1);
        }
        if (!p.time)
          abort('missing "time" parameter in picture {0}.', i + 1);
        p.time_ms = Math.round(p.time * 1000)
      }

      // precalculate left/top/width/height bounding values
      if (p.from)
        jQuery.each([ p.from, p.to ], function (i, from_to) {
          from_to.width = Math.round(p.width * from_to.zoom);
          from_to.height = Math.round(p.height * from_to.zoom);
          from_to.left = Math.round((self_width - from_to.width) * from_to.xrel);
          from_to.top = Math.round((self_height - from_to.height) * from_to.yrel);
        });

      // append the image (or anchor) element to the container
      var elm;
      if (p.href)
        elm = jQuery(format('<a href="{0}"><img src="{1}"/></a>', p.href, p.src));
      else
        elm = jQuery(format('<img src="{0}"/>', p.src));
      if (p.onclick)
        elm.click(p.onclick);
      if (p.alt)
        elm.find('img').attr('alt', p.alt);
      if (p.target)
        elm.find('img').attr('target', p.target);
      elm.appendTo(self);
    }
    speed = undefined; // speed mode has now been translated to full mode

    // find images to animate and set initial css attributes
    var imgs = self.find('img').css({
      position:'absolute',
      visibility:'hidden',
      top:0,
      left:0,
      border:0
    });

    // show first image
    imgs.eq(0).css({ visibility:'visible' });
    if (!sleep)
      imgs.eq(0).css(position_to_css(plan[0], 2));

    // create animation chain
    var countdown = opts.loop;

    function create_chain(i, chainf) {
      // building the chain backwards, or inside out

      if (i % 2 == 0) {
        if (sleep) {
          // still image sleep
          var i_sleep = i / 2,
            i_hide = (i_sleep - 1 + plan.length) % plan.length,
            img_sleep = imgs.eq(i_sleep),
            img_hide = imgs.eq(i_hide);
          var newf = function () {
            img_hide.css('visibility', 'hidden');
            setTimeout(chainf, sleep);
          };
        } else {
          // single image slide
          var i_slide = i / 2,
            i_hide = (i_slide - 1 + plan.length) % plan.length,
            img_slide = imgs.eq(i_slide),
            img_hide = imgs.eq(i_hide),
            time = plan[i_slide].time_ms,
            slide_anim = position_to_css(plan[i_slide], 3);
          var newf = function () {
            img_hide.css('visibility', 'hidden');
            img_slide.animate(slide_anim, time, 'linear', chainf);
          };
        }
      } else {
        if (sleep) {
          // still image cross-fade
          var i_from = Math.floor(i / 2),
            i_to = Math.ceil(i / 2) % plan.length,
            img_from = imgs.eq(i_from),
            img_to = imgs.eq(i_to),
            from_anim = {},
            to_init = { visibility:'visible' },
            to_anim = {};
          if (i_to > i_from) {
            to_init.opacity = 0;
            to_anim.opacity = 1;
            if (opts.doubleFade)
              from_anim.opacity = 0;
          } else {
            from_anim.opacity = 0;
            if (opts.doubleFade) {
              to_init.opacity = 0;
              to_anim.opacity = 1;
            }
          }
          var newf = function () {
            img_to.css(to_init);
            if (from_anim.opacity != undefined) {
              if (opts.doubleFade)
                img_to.animate(to_anim, fade_ms, 'linear');
              img_from.animate(from_anim, fade_ms, 'linear', chainf);
            } else {
              if (opts.doubleFade)
                img_from.animate(from_anim, fade_ms, 'linear');
              img_to.animate(to_anim, fade_ms, 'linear', chainf);
            }
          };
        } else {
          // cross-slide + cross-fade
          var i_from = Math.floor(i / 2),
            i_to = Math.ceil(i / 2) % plan.length,
            img_from = imgs.eq(i_from),
            img_to = imgs.eq(i_to),
            from_anim = position_to_css(plan[i_from], 4),
            to_init = position_to_css(plan[i_to], 1),
            to_anim = position_to_css(plan[i_to], 2);
          if (i_to > i_from) {
            to_init.opacity = 0;
            to_anim.opacity = 1;
          } else {
            from_anim.opacity = 0;
          }
          to_init.visibility = 'visible';
          var newf = function () {
            img_from.animate(from_anim, fade_ms, 'linear');
            img_to.css(to_init);
            img_to.animate(to_anim, fade_ms, 'linear', chainf);
          };
        }
      }

      // if the loop option was requested, push a countdown check
      if (opts.loop && i == plan.length * 2 - 2) {
        var newf_orig = newf;
        newf = function () {
          if (--countdown) newf_orig();
        }
      }

      if (i > 0)
        return create_chain(i - 1, newf);
      else
        return newf;
    }

    var animation = create_chain(plan.length * 2 - 1,
      function () {
        return animation();
      });

    // start animation
    animation();
  });
  return self;
};
